Respiratory valve



FIG. 1 is a front perspective view of a respiratory valve;

FIG. 2 is a rear perspective view of the respiratory valve;

FIG. 3 is a front view of the respiratory valve;

FIG. 4 is a left side view of the respiratory valve;

FIG. 5 is a rear view of the respiratory valve;

FIG. 6 is a top view of the respiratory valve; and,

FIG. 7 is a bottom view of the respiratory valve.

Portions of the drawings shown within broken lines form no part of the claimed design. 

CLAIM The ornamental design for a respiratory valve, substantially as shown and described. 